An easily polymerizable substance is a substance having the polymerizability, which easily causes a polymerization reaction by heat or the like, and is industrially useful as a raw material for forming various compounds or polymers. Among the easily polymerizable substance, as a monomer which is industrially particularly useful, there may be mentioned (meth)acrylic acid. (Meth)acrylic acid is widely used for forming an acrylic fiber copolymer, and an adhesive such as an emulsion and, additionally, is useful also in the field such as paint, fiber procession, leather, construction material and the like, and is indispensable in many chemical fields.
In production of such the easily polymerizable substance, in order to respond to many demands, scale up of a manufacturing facility is required. For example, in production of (meth)acrylic acid, a process by a catalytic gas phase oxidation reaction of propylene or the like has advantage in that an inexpensive manufacturing material can be used, and is industrially advantageous. In this case, since a low boiling point substance, a high boiling point substance and the like are produced as by-products, in addition to (meth)acrylic acid, these by-products and other impurities are separated and removed by a purification system consist of a distillation column and the like, and purified high quality (meth)acrylic acid is supplied.
When an amount of such the easily polymerizable substance such as (meth)acrylic acid and the like to be produced is increased, since there is a limit for one reactor to produce, it is considered to produce the substance in plural reactors. In this case, products obtained in plural reactors are supplied to a purification system and, when products are supplied to a purification system separately, there is a possibility that the easily poylmerizable substance is polymerized in a manufacturing apparatus of a purification system, and manufacturing must be stopped. In such the industrial production, when production is stopped, a production amount can not be stably maintained, this cause troubles in supply of an easily poylmerizable substance such as (meth)acrylic acid and the like which is useful in various fields. Therefore, when the production amount of an easily polymerizable substance is increased, there is room for contrivance to realize stable operation of a purification system and stably supply a purified high quality product.
The prior art cannot be found which describes the technique for realizing stable operation of a purification system, upon obtaining an easily polymerizable substance such as (meth)acrylic acid and the like in plural reactors.